| 1. |
- Antzutkin, Oleg, et al.
(author)
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13C and15N-chemical shift anisotropy of ampicillin and penicillin-V studied by 2D-PASS and CP/MAS NMR
- 1998
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In: Journal of magnetic resonance. - : Elsevier BV. - 1090-7807 .- 1096-0856. ; 135:1, s. 144-155
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Journal article (peer-reviewed)abstract
- The principal values of the chemical shift tensors of all13C and15N sites in two antibiotics, ampicillin and penicillin-V, were determined by 2-dimensionalphaseadjustedspinningsideband (2D-PASS) and conventional CP/MAS experiments. The13C and15N chemical shift anisotropies (CSA), and their confidence limits, were evaluated using a Mathematica program. The CSA values suggest a revised assignment of the 2-methyl13C sites in the case of ampicillin. We speculate on a relationship between the chemical shift principal values of many of the13C and15N sites and the β-lactam ring conformation
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| 2. |
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| 3. |
- Antzutkin, Oleg, et al.
(author)
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Coherence transfer signals in the rotational resonance NMR of a spinning single crystal
- 2000
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In: Journal of magnetic resonance. - : Elsevier BV. - 1090-7807 .- 1096-0856. ; 147:1, s. 147-151
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Journal article (peer-reviewed)abstract
- A recent analysis of rotational resonance lineshapes (M. Helmle et al., J. Magn. Reson. 140, 379-403, 1999) predicted the existence of coherence transfer signals, which are generated by mechanically induced coherence transfer during the detection process. These signals correspond to the generation of observable coherences at spin sites that have no magnetization at the beginning of the observation interval but which acquire coherence while the detection is underway. The coherence transfer signals disappear for powder samples in conventional magic-angle-spinning solid-state NMR experiments. In this Communication, we report the successful detection of coherence transfer signals in rotor-synchronized experiments performed on a single crystal of [1,2-13C2]glycine.
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| 4. |
- Antzutkin, Oleg, et al.
(author)
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Suppression of sidebands in magic-angle-spinning nuclear magnetic resonance : general principles and analytical solutions
- 1994
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In: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 100:1, s. 130-140
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Journal article (peer-reviewed)abstract
- Several theoretical and experimental aspects of sideband suppression in the nuclear magnetic resonance (NMR) spectra of rotating solids are considered. The principles of sideband suppression are explored using general symmetry arguments and previous treatments are examined critically. Analytical solutions are given for sideband suppression pulse sequences employing four, five, six, and nine pulses. The analytical solutions for four pulses are complete. Experimental demonstrations are given. The Journal of Chemical Physics is copyrighted by The American Institute of Physics.
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| 5. |
- Song, Zhiyan, et al.
(author)
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Sideband suppression in magic-angle-spinning NMR by a sequence of 5 π pulses
- 1993
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In: Solid State Nuclear Magnetic Resonance. - 0926-2040 .- 1527-3326. ; 2:3, s. 143-146
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Journal article (peer-reviewed)abstract
- We report a symmetrical sequence of 5 π pulses for total sideband suppression in magic-angle-spinning NMR. The sequence is almost evenly spaced and shorter than previous 4 and 6 π pulse methods.
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